Abstract

Acoustic modes propagating in shallow oceans interact with internal‐wave‐induced oscillations in the thermocline to produce fluctuations in the acoustic field that govern spatial and temporal coherence. Such interactions are described by both adiabatic‐mode path‐integral theory and coupled‐mode scattering‐matrixtheory. In both theories there occurs an integral over the water depth that sums the interaction between the buoyancy, acoustic modes, and internal‐wave modes. This paper explores the strength of that interaction for the Transverse Acoustic Variability Experiment, which took place in the northern limit of the East China Sea in 65–80 m of water. A towed CTD chain provided measurements of the density and sound‐speed profiles required to compute the necessary acoustic and internal‐wave modes. Within this environment, two main conclusions pertain. First, with respect to internal‐wave mode contributions, the first mode contributes most significantly with a lesser contribution from the second mode and negligible contributions from higher modes. Second, with respect to acoustic mode contributions, the adiabatic mode contribution is most significant with lesser contributions from adjacent modes, and negligible contributions from widely separated mode pairs. [Work supported by the Office of Naval Research.]